Omen of local roofing and preventive measures

The occurrence of local roofing is mainly determined by the rock properties of the roof and the support of the bracket to each roof. When the roof is broken and the joints are developed, the roof will not occur when the support is not carried out. In areas where geological conditions change, roofing is also prone to occur. Sometimes, although the top plate is relatively stable, ignoring the quality of the bracket specifications and violating the operating procedures may cause local roofing.

The omen of the local roof is mainly manifested in: the working face encounters a small geological structure; the crack in the roof is opened, the crack increases, and an abnormal sound is emitted when the top is knocked; the crack in the roof crack has a live cockroach, and there is a drop and a fall. phenomenon, after the first big or small; coal layer with the top plate contact surface, an extremely thin continuous sheet off gangue; water spray droplets dripping from the top plate cleavage planes.

Prevention part roof can proceed from the following aspects: Supporting embodiment stone and slate properties must adapt to the top; rear pillar to timely shearer mining; confidential delivery overall displacement necessary safety measures; face down to the outlet There are special supports; (According to the provisions of the "Safety Regulations for Coal Mines", it is generally adopted to lift the shed in the upper and lower leveling roads, to lift the sheds at the nose and the tail of the machine, and sometimes to add dense pillars or rafts, etc. Measures to be specially supported. Prevent the cannon from falling into the shed; do a good job of returning the column to the top. The top of the column must be timely. When the top distance exceeds the operating regulations, coal mining is prohibited. After the column is returned, the roof still does not fall. , in excess of requirements flap top distance must be taken manually caving or other effective measures to force roof adhere to a regular cycle of operation; adhere to perform the necessary systems (such as knock to help Acmeward system, acceptance stent system, job responsibility system, metal Bracket inspection system, handover system, roof analysis system, etc.).

Signs and precautions

The coal mining face is continuously advancing, and the control top area is gradually increased. When the thickness of the direct top is gradually collapsed, and the hard old top is overhanging, a natural layer is formed in the roof rock layer of the working face. The pressure arch changes the pressure of the coal wall, causing the pressure on the working face to concentrate. In this case, if the total supporting force of the working face support to the top plate cannot be adapted to the requirement of maintaining the stable sinking of the top plate, a large roof (or cut top) may occur.

The harbinger of the big roof is generally divided into a roof warning, including the continuous sound of the top plate. This is due to the sound that occurs when the direct top and the old top are separated from the floor or the top plate. The roof rock stratum is broken, fallen, and dropped, and the drop is generally changed from less to less. The crack in the roof is increased or the crack is opened and a large amount of sinking is generated. As the pressure increases before the roof rises, the coal wall becomes soft and the coal is softened. When using an electric drill to drill the eye, the eyesight is labor-saving; when the coal is cut with a shearer, the load is reduced. When the wooden bracket is used, the bracket is broken and sounds a lot; when the metal pillar is used, the pressure of the top plate causes the living column to sink quickly, and the sound of "squeaky, slightly" is continuously emitted, and the pillar is trembled. When the working face uses the spliced ​​top beam, the top beam wedge is ejected or squeezed due to the impact pressure of the top plate, commonly known as the "flying wedge". When the bottom plate is soft or the bottom plate is left with a bottom stone and the bottom coal is lost, the pillars are inserted into the bottom plate in a large amount. The gas content of the working face is increased or the water is increased. The coal seam containing gas has a sudden increase in gas emission before the roof. There is a roof that is drenched, and the amount of water is increased.

The following measures can be taken to prevent the big top in response to the performance of the big top. First, master the top plate cycle of the work surface to control the law. When determining the total supporting force of the working face support, the initial pressure and periodic pressure of the top plate must be considered. If the total support force of the bracket can only adapt to the normal roof pressure, it will pose a serious threat to the working surface when there is a period of pressure. When the total supporting force of the bracket is insufficient to cope with the cycle, the law of the movement of the roof is mastered, the support is strengthened before the pressure is applied, the bracket is increased, and various safety measures are taken to prevent the roof from falling. Therefore, it is necessary to have spare support materials for the mining face. Secondly, the coal mining face should have reasonable bracket specifications and support density. In addition, we must speed up the advancement of the work surface. Because the progress of the working surface is slow, the amount of roof subsidence is large, so the top plate is incomplete, the wooden bracket is damaged more, and the pressure on the metal pillar is also large. Due to the slow progress and the large number of pillars being damaged, the total supporting force of the working surface is reduced, which makes it easy to push the working surface. Therefore, the speed of the work surface should be accelerated.

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